Apparatus for recording or reproducing sounds.



T. A. EDISON.

APPARATUS FOR RECORDING 0R REPRODUGING SOUNDS. APPLICATION FILED MAY 24, 1905.

963,362. I Patented July 5, 1910.

Witnesses In vefitoz' Attorney.

THOMAS A. EDISON, OF LLEWELLYN PARK, ORANGE, '.l\l'I1 -W' JERSEY.

APPARATUS FOR. RECQRDING OB. REPBODUCING: SOUNDS.

Specification of Letters I'atent.

Application filed May 24, 1905. Serial No. 261,950.

Patented Jul 5,1910.

To all whom it may concern:-

Be it known that I, THOMAS A. Enrson, a citizen of the United States, residing at Llewellyn Park, Orange, in the county of Essex and State of New Jersey, have invented certain Improvements Apparatus for Recording or Reproducing Sounds,

" (Case 13,) ofwhichi the followingis a description.

My invention relates to various new and useful improvements in apparatus for recording or reproducing sounds, and my object is to provide an apparatus for the purpose which shall permit a more accurate recording of the sound waves free from waves or disturbances, due to the recording mechanism itself, and a more accurate reproduction of the same than is possible by methods and apparatus heretofore known.

In an application for Letters Patent filed on even date herewith, and relating to methods of recording or reproducing sounds, I have pointed out the cause or'origin of the false, discordant and inharmonic sounds which are created within the recording mechanism, and which become recorded to afiect the character of the reproduction.

VV'th diaphragms as now made a thin plate, or a series of superposed plates, of greatly reduced diameter has been tightly clamped at the edge, so that any vibration must take place by the flexing or bending of the diaphragm itself. Such a diaphragm, moreover, acts practically as a reed and produces a note of its own, so that it vibrates sympathetically with certain notes within the rangeof music, and therebyproduces inharmonic resultant tones which become recorded with the other sounds. Furthermore, such a diaphragm, in vibrating, vibrates locally so as to form a large number of nodes, as has been demonstrated by the production of the so-called Chaladni figures, and these vibratable local areas are also probably responsive to certain musical tones or overtones to result in the production of certain extraneous sounds, whlch become recorded and mar the reproduction. More over, such a diaphragm, owing to its clamped edges, vibrates with relative diliiculty, and, hence, is not as sensitive as it should be; and, since it vibrates locally, the local vibrations are not communicated to the recording stylus, and, consequently, a pro-; portionate loss of energy takes place toweaken the recorded sounds.

Notwithstanding the inherent lack ofsensitiveness which is characteristic of ordinary diaphragms, the fact is that in the attempt to obviate the production of the inharmomc sounds referred to, it has been the practice to pur osely further diminish the sensitiveness 0 the diaphragm to such an extent that the volume or strength of the inharmonic sounds is reduced so that they are not so prominent; but this practice has been ineffective for the purpose, and the diaphragms are' so lacking in sensitiveness that the delicate overtones which accompany the fundamental tones, and which give to music its pleasing quality, are weakened in most cases so as'to be. practically inaudible, while distortion of the sound sought to be recorded is produced.

In correctingthe faults which exist in diaphragms as now constructed, I have produced a diaphragm which is entirely free from any'audible fundamental tone or overtone of its own, and which, therefore, does not vibrate sympathetically with any tones within the range of music. I thus revent not only the distortion of the 'origina sound waves, but I also revent the production of inharmonic sound d, such as are roduced with diaphragms as heretofore ma e. Furthermore, my improved diaphragm can be and is extremely sensitive, so as toaccurately respond to and efi'ect the recording of all fundamental tones as well as their overtones. Finally, with my improved diaphragm, inertia due to Wei ht is reduced to a minimum, and, consequent y, 'false vibration caused by overthrow. and retardation is largely overcome, this being especially true in the case of vibrations of high frequency. I attain this result by employing a rigid diaphragm of a novel t pe, which, instead of vibrating in the usua .way, vibrates as a whole, the entire displacement taking place at the edges, and llemploy with that diaphragm at the periphery thereof an extension or continuation-0f soft pliable yielding material so as to operate practically vas a hinge, the whole havmg no audible tomenot set anyspecial local area in vibration Isufiicient to produce Ohaladni figures, so that the whole vibrates or follows the sound Z waves with great accuracy by beingforced.

In order that the invention. may be better understood, attention is directed to the acdiaphragm; Fig. 2, a similar view of a reproducing apparatus embodying my improvements, showing a dished or concave diaphragm; Fig. 3, a similar view of a recording apparatus, embodying my inventionand showing a diaphragm that is both corrugated and dished; Fig. 4, a plan view of 15- Fig. 5, a plan view of the diaphragm shown the diaphragm shown in Figs. 1 and 3, and

in Fig. 2.

In all of the above views, corresponding parts are represented by-the same numerals of reference. v

A diaphragm 1, is shown in Figs.v 1 and 4: as being, provided with concentric corrugations, made so deep that the diaphragm acts as a rigid body to sound waves, and vibrates to and fro like a piston without bending or flexing at the center, as with ordinary diaphragms clamped at the edges. The rigidity of the diaphragm is such that if clamped at the edges in the usual way it would not vibrate under the efiect of sounds as ordinarilyused in this art. Furthermore, the diaphragm is so rigid that it is free from local vibrations which with ordinary diaphragms produce Chaladni figures. The diaphragm shown in Figs. 2 and 5 is dished or scooped for the same purpose, but this is I not quite so efiective! when deep corrugations are used. In any case, the diaphra should be as light as possible, and be stlfi enough to vibrate as a rigid body. t will, therefore, be understood, that the a diaphragms may be both dished and corrugated, as shown in Fig. 3, in order that metal of exceeding thinness can be used.

Preferably the diaphragm is made of very thin metallic magnesium, which is extremely light and very rigid when corrugated, particularly when both dished and corrugated, and very thin sheets can be used-much. thinner in fact than with glass diaphragms as now commonly employed. To this rigid piston-like diaphragm 1s secured around its outer edge a'ring 2, preferably of soft rubber, which is held in place by shellac or other cement, so as to form practically a yielding extension of the dia hragm, and which, when the diaphragm vibrates to and fro, vibrates practically as a hinge having a negligible resistance. The rim 2, may be made of other materials than ru ber such as leather, paper, thin collodion, etc., but thin rubber tissue is preferable for obtaining great sensitiveness. This ring 2, is cemented or otherwise secured without tension to any suitable arrangement of head orbody eeasea 4, carrying a suitable recording stylus 5 (Figs. 1 and 3), is cemented or otherwise secured to the" diaphragm. When used with a reproducer, a reproducing stylus 6 (Fig. 2) is preferably pivoted to the usual floating weight and connected to the diaphragm" by a link in the usual way.

In order to take the thrust imposed by the rotation of the recordin surface with respect to the recording sty us, I extend a link 7, between the foot 4, and an arm 8, depending from the head 3, said link being made preferably of wood so-as to be very light, and having its vertical dimension greater than its transverse dimension, and of constant-ly varying section reduced to a very thin leaf at the end where it is' secured to the arm 8, whereby the formation of nodes will be prevented and the fundamental tone of the link be so grave as to be below the range of ordinary music, as I describe and claim in my application filed November 13, 1903, Serial 'No. 180,998. When the diaphragm vibrates it follows the very slight are which the free end of the link describes, the yielding ring 2, permitting the diaphragm to move laterally to the desired extent, so that there is no cramping in op- I erat-ion.

Since the diaphragm can vibrate only to of'the ring 2, extending between the diaphragm and the cement which holds the ring in place. This yieldin section can have no audible local disturblng tone; and hence, all of its movements, as well as those of the diaphragm, are forced, and the recorder is, therefore, caused to accurately follow the sound waves.

Since the action of the diaphragm is analogous to that of a piston subjected to pressure, first on one side and'then on the other, it follows that any movements of the yielding section or bulging thereofbeyondthe movement of the diaphragm will diminish the amplitude of the latter, and for this reason the yielding section should be very thin and the area very small. In practice, ll increase the diameter of the rigid diaphragm to as great an extentin proportion to the yielding material as possible, the latter being usually about six per cent. of the whole area. In this way I concentrate nearly the whole of the condensations and rarefactions of the sound waves upon the rections m Letters Patent No. 963,362.,

leave the record, particularly when the recorded waves are very deep or of high frequency. Furthermore, the great lightness of the diaphragm materially reduces wear upon the recorded surface. In the next place, since the diaphragm is free from any fundamental tone or overtone of its own, it cannot respond sym athetically with any of the recorder soun s to thereby distort the reproduction and make it inharmonic. Finally, since the diaphragm is incapable of vibrating locally, the creation of extraneous sounds from that cause in the reproduction is also overcome.

IYhile- I have described my improved apparatus in connection with the recording and reproduction of sounds phonographlcally, and wherein the recorder forms, or the reproducer follows, a record of varying depth, it will be understood that the apparatus can be effectively utilized with machines of the gramophone type, wherein a zigzag record groove is formed, it being only necessary in the latter case to connect the diaphragm with a recorder adapted to form, or with a reproducer adapted to follow, such a zig-zag record groove.

Having now described my invention what I claim as new therein and desire to secure by Letters Patent is as follows:

1. In apparatus for recording or reproducing sounds, the combination of a body and a very thin diaphragm formed of alight metal, said diaphragm being dished or concave, and provided with deep concentric corrugations, said diaphragm being connected to said body by a hinge of a material the case in the Patent Office.

" [SEAL] having greater pliability than that of the diaphragm, substantially as set forth.

2. In apparatus for recording or reproducing sounds, the combination of a body and a very thin diaphragm formed of magnesium, said diaphragm being dished or concave, and provided with deep concentric corrugations, said diaphragm being connected to said body by a hinge of a material having greater pliability than that of the diaphragm, substantially as set forth.

3. In apparatus for recording or reproducing sounds, a very thin diaphragm formed of a light rigirLand elastic metal, said diaphragm being dished or concave for practically its whole width, and provided throughout with deep concentric corrugations, substantially as set forth.

t. In apparatus for recording or reproducing sounds, the combination with a body and a diaphragm secured thereto by a hinge of yielding material so as to be capable of lateral movement, of a stylus connected to said diaphragm and a light rod anchored at one end and connected at its other end to said stylus for receiving the thrust thereof, said rod being so shaped as to give forth no audible tone in vibrating, substantially as set forth.

5. A diaphragm made of metallic magnesium and having a concave portion formed with concentric corrugations, substantially as set forth. a p

6. A diaphragm made of metallic magnesium and united to a circumferential sechaving greater pliability than magnesium and which is adapted to operate as a hinge THOS. A. EDISON.

IVitnesses:

FRANKL. DYER,

ANNA R. KLEHM.

It is hereby certified that in Letters Patent h o. 963,362, granted July 5, 1910, upon the application of Thomas A. Edison,- of Llewellyn Park,- Orange, New Jersey, for an improvement in Apparatus for Recording or Reproducing Sounds, errors appear in the printed specification requiring correction as follows: Page 2, a line 37, after the word effective the word as should be inserted; page 3, line 19, I the word recorder should raid-recorded; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of I Sigged and sealed this QOth-day of September, A. D., 1910.

C. C. BILLINGS,

Acting Commissioner of Patents.

tion .of small area composed of material 

